1. Field of the Invention
The present invention relates to an ignition coil for an engine.
2. Description of the Prior Art
In case of an ignition coil for an engine, it has been a general practice to connect a terminal end of a coil strand at an end of a secondary coil to a terminal member for outside connection, by pulling the terminal end of the coil strand out of a coil bobbin, positioning said terminal end in a U-shaped groove of said terminal member and then electrically welding the coil strand (copper wire) positioned in the groove to the terminal member by applying heavy current to the groove from outside of the terminal member while crushing the groove of the terminal member. Such electrical welding connection is so-called as "fusing connection".
In such fusing connection, if the fusing connection is effected, while crushing a U-shaped groove 32 of a terminal member by an electric welding machine 34 in such state that a coil strand 33 is positioned on a bottom of the U-shaped groove, as shown in FIG. 7(a) and FIG. 7(b), a gap may be formed in the crushed part of the bottom of the U-shaped groove 32, that results in incomplete electric welding of the coil strand 33 passing such crushed part.
On the other hand, if the fusing connection is effected while crushing the U-shaped groove 32 in such state that the coil strand 33 passes through a shallow part in the U-shaped groove 32, as shown in FIG. 8(a) and FIG. 8(b), a complete connection cannot be attained.
In order to avoid such incomplete connection, it has been heretofor necessary to connect the coil strand to the terminal member, by manually positioning the coil strand 33 relatively to the U-shaped groove 32 so that the coil strand 33 passes through a center in the U-shaped groove 32 of the terminal member, as shown in FIG. 9(a) and FIG. 9(b), and then effecting the fusing connection while crushing the U-shaped groove 32.